Closures for glass jars are of two main types:
_Metal screwband and flat metal lid_ with sealing compound. To use this
type, wipe jar rim clean after produce is packed. Put lid on, with
sealing compound next to glass. Screw metal band down tight by hand.
When band is tight, this lid has enough give to let air escape during
processing. Do not tighten screw band further after taking jar from
canner.
Screw bands that are in good condition may be reused. You may remove
bands as soon as jars are cool. Metal lids with sealing compound may be
used only once.
_Porcelain-lined zinc cap_ with shoulder rubber ring. Fit wet rubber
ring down on jar shoulder, but don’t stretch unnecessarily. Fill jar;
wipe rubber ring and jar rim clean. Then screw cap down firmly and turn
it back ¼ inch. As soon as you take jar from canner, screw cap down
tight, to complete seal.
Porcelain-lined zinc caps may be reused as long as they are in good
condition. Rubber rings should not be reused.
[Illustration: 76944B]
Metal screw band
Metal lid with sealing compound
Seals here
[Illustration: 76944B]
Porcelain lined screw cap
Rubber
Seals here